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Alterations of myoepithelial cells in the rat mammary gland during pregnancy, lactation and involution, and after estradiol treatment
Author(s) -
Jin Hua Shu,
Umemura Shinobu,
Iwasaka Toshiki,
Osamura R. Yoshiyuki
Publication year - 2000
Publication title -
pathology international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.73
H-Index - 74
eISSN - 1440-1827
pISSN - 1320-5463
DOI - 10.1046/j.1440-1827.2000.01064.x
Subject(s) - myoepithelial cell , lactation , involution (esoterism) , mammary gland , endocrinology , medicine , weaning , hormone , pregnancy , biology , immunohistochemistry , andrology , breast cancer , cancer , consciousness , neuroscience , genetics
Hormone‐induced alterations of myoepithelial cells in the mammary gland have not been fully investigated. The aim of the present study was to examine whether myoepithelial cells are altered in response to hormonal conditions. The immunohistochemical findings of smooth muscle actin for myoepithelial cells were studied during pregnancy, lactation and involution, and after estradiol dipropionate (ED) treatment (50, 500, 1000 μ g/kg per week for 1–4 weeks) using a total of 71 Wistar female rats. Myoepithelial cells showed a stratified appearance around ducts during pregnancy, extended cytoplasmic processes with wider distance during lactation, and vacuolated cytoplasm after weaning. ED treatment (50–1000 μ g/kg per week) for 1 week increased myoepithelial cells to a variable degree, achieving a level similar to that in pregnancy, but ED treatment for 4 weeks reduced them as the dose elevated. The present study showed that the myoepithelial cells became hyperplastic or hypertrophic by low‐dose ED treatment within the physiological range, while weaning pups, and excess high‐dose ED treatment beyond the physiological range or prolonged ED treatment induced reduction of the myoepithelial cells. Results indicate that myoepithelial cells themselves are also altered by hormonal conditions coordinating the mammary gland development.